scholarly journals Spectral nudging in the Tropics

2020 ◽  
Author(s):  
Breogán Gómez ◽  
Gonzalo Miguez-Macho
Keyword(s):  
Large Scale ◽  
Model Solution ◽  
Wave Number ◽  
Limited Area ◽  
Spectral Nudging ◽  
Novel Approach ◽  
Starting Point ◽  
Time Required ◽  
Two Parameters ◽  
The Impact

Abstract. Spectral nudging allows forcing a selected part of the spectrum of a model's solution with the equivalent part in a reference dataset, such as an analysis, reanalysis or another model. This constrains the evolution in certain scales, typically the synoptic ones, while allowing the others to evolve freely. In a limited area model (LAM) setting, spectral nudging is commonly used to impose the large-scale circulation in the interior of the domain, so that the high resolution features in the LAM's forecast are consistent with the global circulation patterns. In a previous study developed over a Mid-Latitude domain, we investigated two parameters of spectral nudging that are often overlooked despite having a significant impact on the model solution. First, the cut-off wave number, which is the parameter determining the scales that are nudged and has a critical impact on the spatial structure of the model solution. Second, the spin-up time, which is the time required to balance the nudging force with the model internal climate and roughly indicates the starting point from when the results of the simulation contain useful information. The question remains if our conclusions for Mid-Latitudes are applicable to other areas of the planet. Tropical Latitudes offer an interesting testbed as its atmospheric dynamics has unique characteristics with respect to that further North and yet it is the result of the same underlying physical principles. We study the impact of these two parameters in a domain centred in the Gulf of Mexico, with a particular aim to evaluate their performance related to hurricane modelling. We perform 4-day simulations along 6 monthly periods between 2010 and 2015, testing several spectral nudging configurations. Our results indicate that the optimal cut off wavenumber lies between 1000 Km and 1500 Km depending on the studied variable and that the spin-up time required is at least 72 h to 96 h, which is consistent with our previous work. We evaluate our findings in four hurricane cases, allowing for at least 96 h of spin-up time before the system becomes a tropical storm. Results confirm that the experiments with cut-off wavenumbers near the Rossby Radius of Deformation perform best. We also propose a novel approach in which a different cut-off wavenumber is used for each variable. Our tests in the hurricane cases show that the latter set up is able to outperform all of the other spectral nudging experiments when compared to observations.

scholarly journals Reservoir-Induced Land Deformation: Case Study from the Grand Ethiopian Renaissance Dam

2021 ◽  
Vol 13 (5) ◽  
pp. 874
Author(s):  
Yu Chen ◽  
Mohamed Ahmed ◽  
Natthachet Tangdamrongsub ◽  
Dorina Murgulet
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Nile River ◽  
Reservoir Volume ◽  
Novel Approach ◽  
Land Deformation ◽  
Large Scale Land ◽  
The Impact

The Nile River stretches from south to north throughout the Nile River Basin (NRB) in Northeast Africa. Ethiopia, where the Blue Nile originates, has begun the construction of the Grand Ethiopian Renaissance Dam (GERD), which will be used to generate electricity. However, the impact of the GERD on land deformation caused by significant water relocation has not been rigorously considered in the scientific research. In this study, we develop a novel approach for predicting large-scale land deformation induced by the construction of the GERD reservoir. We also investigate the limitations of using the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission to detect GERD-induced land deformation. We simulated three land deformation scenarios related to filling the expected reservoir volume, 70 km3, using 5-, 10-, and 15-year filling scenarios. The results indicated: (i) trends in downward vertical displacement estimated at −17.79 ± 0.02, −8.90 ± 0.09, and −5.94 ± 0.05 mm/year, for the 5-, 10-, and 15-year filling scenarios, respectively; (ii) the western (eastern) parts of the GERD reservoir are estimated to move toward the reservoir’s center by +0.98 ± 0.01 (−0.98 ± 0.01), +0.48 ± 0.00 (−0.48 ± 0.00), and +0.33 ± 0.00 (−0.33 ± 0.00) mm/year, under the 5-, 10- and 15-year filling strategies, respectively; (iii) the northern part of the GERD reservoir is moving southward by +1.28 ± 0.02, +0.64 ± 0.01, and +0.43 ± 0.00 mm/year, while the southern part is moving northward by −3.75 ± 0.04, −1.87 ± 0.02, and −1.25 ± 0.01 mm/year, during the three examined scenarios, respectively; and (iv) the GRACE-FO mission can only detect 15% of the large-scale land deformation produced by the GERD reservoir. Methods and results demonstrated in this study provide insights into possible impacts of reservoir impoundment on land surface deformation, which can be adopted into the GERD project or similar future dam construction plans.

scholarly journals Continuous high-resolution midlatitude-belt simulations for July–August 2013 with WRF

2017 ◽  
Vol 10 (5) ◽  
pp. 2031-2055 ◽  
Author(s):  
Thomas Schwitalla ◽  
Hans-Stefan Bauer ◽  
Volker Wulfmeyer ◽  
Kirsten Warrach-Sagi
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Large Scale ◽  
Temperature Fields ◽  
Surface Model ◽  
Limited Area ◽  
Data Set ◽  
Latitude Belt ◽  
Simulated Precipitation ◽  
The Impact

Abstract. Increasing computational resources and the demands of impact modelers, stake holders, and society envision seasonal and climate simulations with the convection-permitting resolution. So far such a resolution is only achieved with a limited-area model whose results are impacted by zonal and meridional boundaries. Here, we present the setup of a latitude-belt domain that reduces disturbances originating from the western and eastern boundaries and therefore allows for studying the impact of model resolution and physical parameterization. The Weather Research and Forecasting (WRF) model coupled to the NOAH land–surface model was operated during July and August 2013 at two different horizontal resolutions, namely 0.03 (HIRES) and 0.12° (LOWRES). Both simulations were forced by the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis data at the northern and southern domain boundaries, and the high-resolution Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) data at the sea surface.The simulations are compared to the operational ECMWF analysis for the representation of large-scale features. To analyze the simulated precipitation, the operational ECMWF forecast, the CPC MORPHing (CMORPH), and the ENSEMBLES gridded observation precipitation data set (E-OBS) were used as references.Analyzing pressure, geopotential height, wind, and temperature fields as well as precipitation revealed (1) a benefit from the higher resolution concerning the reduction of monthly biases, root mean square error, and an improved Pearson skill score, and (2) deficiencies in the physical parameterizations leading to notable biases in distinct regions like the polar Atlantic for the LOWRES simulation, the North Pacific, and Inner Mongolia for both resolutions.In summary, the application of a latitude belt on a convection-permitting resolution shows promising results that are beneficial for future seasonal forecasting.

scholarly journals Measuring and assessing the impact of using volunteers in UK libraries: issues and methods

2014 ◽  
Vol 15 (3) ◽  
pp. 112-121 ◽  
Author(s):  
Judith Broady-Preston
Keyword(s):  
Systematic Review ◽  
Large Scale ◽  
Third Sector ◽  
Professional Staff ◽  
Research Centre ◽  
Content Type ◽  
Qualitative Approaches ◽  
Starting Point ◽  
Third Sector Organisations ◽  
The Impact

Purpose – The purpose of this paper is to examine a range of issues and methods in relation to measuring the impact of volunteer labour on the design and delivery of all types of library services. With the increasing use of volunteers to deliver library and information services in all sectors, managers need to assess their effectiveness and evaluate the impact of their use in relation to operational service design and delivery, and on the development of the profession and professional practice as a whole. Presented here is an initial scoping study, outlining a range of issues, methods and challenges for more detailed future investigation. Design/methodology/approach – A number of methodological challenges and perspectives are identifiable. Contemporary libraries exhibit increasing similarities with Third Sector organisations, namely a complex stakeholder community, and increasing use of volunteers to supplement or replace services delivered by professional staff. Therefore, a starting point for the research is a systematic review and analysis of the methodologies developed by the Third Sector Research Centre, and those studies in the ESRC contemporary Developing Impact Evaluation strand. As a rich picture is required, both quantitative and qualitative approaches are necessary, with the overall study adopting a mixed methods approach. Findings – This paper reports the findings of the preliminary documentary analysis, literature review and scoping aspects of a large-scale study. Originality/value – Research undertaken to date (June 2014) has failed to identify any published systematic review and examination of these issues.

Impact of Privacy Issues on Successful Implementation of Personalized Medicare System

2019 ◽  
Vol 10 (3) ◽  
pp. 96-115
Author(s):  
Sandip Bisui ◽  
Subhas C. Misra
Keyword(s):  
Large Scale ◽  
Healthcare Management ◽  
Genomic Variation ◽  
Successful Implementation ◽  
Related Factors ◽  
Privacy Concerns ◽  
Novel Approach ◽  
Impact Of Technology ◽  
The Impact ◽  
Privacy Issues

Personalized medicare systems is an emerging field of research, which bears the potential to significantly reduce healthcare expenditures and treatment errors and thereby to revolutionize the entire treatment procedure. In this novel approach, genomic variation in different individuals is duly taken into consideration. However, there exist several serious issues (e.g. privacy concerns) that provide hindrance to large-scale adoption of this medicare system. The main objective of this study has been to identify the privacy issues and to evaluate their impact on successful implementation of this novel medical treatment. The methodology used is empirical and is based on a survey-based post facto procedure. The data collected from the survey are analyzed by using the method of structural modelling analysis. This is an original study in the realm of healthcare management, which reveals that the technology related factors and privacy concerns have considerable impact on the successful implementation of personalized medicare system on a large scale. But the privacy concerns have no significant moderating effect on the impact of technology related factors, so far, the success of implementation of personalized medicine is concerned.

scholarly journals On the Time Evolution of Limited-Area Ensemble Variance: Case Studies with the Convection-Permitting Ensemble COSMO-E

2018 ◽  
Vol 76 (1) ◽  
pp. 11-26 ◽  
Author(s):  
Christina Klasa ◽  
Marco Arpagaus ◽  
André Walser ◽  
Heini Wernli
Keyword(s):  
Case Studies ◽  
Time Evolution ◽  
Large Scale ◽  
Horizontal Wind ◽  
Limited Area ◽  
Convective Activity ◽  
Moist Convection ◽  
Domain Boundaries ◽  
Large Scale Flow ◽  
The Impact

Abstract Dynamical processes determining the time evolution of difference kinetic energy (DKE) in a limited-area domain are investigated with the convection-permitting ensemble model COSMO-E for a forecasting period of 4 days. DKE is quantified by means of ensemble variance of the irrotational and nondivergent horizontal wind. For three case studies characterized by contrasting predictability levels of precipitation, it is shown that DKE of the irrotational wind strongly increases during periods of solar-forced moist convective activity and decreases when the latter ceases. The response of DKE of the nondivergent wind is also clearly related to the convective activity, but delayed by a few hours, pointing to interactions between both wind components. Apart from the impact of moist convection, DKE of the nondivergent wind is primarily governed by large-scale advection, imposed at the lateral domain boundaries of the limited-area ensemble. This forcing may also sustain or increase DKE of the irrotational wind when moist convection is absent. Consequently, the large-scale flow and diurnal solar forcing, associated with higher spatiotemporal predictability, determines the overall evolution of the limited-area ensemble variance of the horizontal wind, which increases in the presence of moist convective activity or strong synoptic-scale forcing, and stagnates or decreases otherwise, rendering forecasts of convection-permitting ensembles valuable beyond the very short forecast range.

scholarly journals On the Impact of the Choice of Global Ensemble in Forcing a Regional Ensemble System

2016 ◽  
Vol 31 (2) ◽  
pp. 515-530 ◽  
Author(s):  
Florian Weidle ◽  
Yong Wang ◽  
Geert Smet
Keyword(s):  
Large Scale ◽  
Ensemble Forecasting ◽  
Ensemble Prediction ◽  
Lateral Boundary Condition ◽  
Limited Area ◽  
Prediction System ◽  
Ensemble Prediction System ◽  
Driving Model ◽  
Environmental Prediction ◽  
The Impact

Abstract It is quite common that in a regional ensemble system the large-scale initial condition (IC) perturbations and the lateral boundary condition (LBC) perturbations are taken from a global ensemble prediction system (EPS). The choice of global EPS as a driving model can have a significant impact on the performance of the regional EPS. This study investigates the impact of large-scale IC/LBC perturbations obtained from different global EPSs on the forecast quality of a regional EPS. For this purpose several experiments are conducted where the Aire Limitée Adaption dynamique Développement International–Limited Area Ensemble Forecasting (ALADIN-LAEF) regional ensemble is forced by two of the world’s leading global ensembles, the European Centre for Medium-Range Weather Forecasts’ Ensemble Prediction System (ECMWF-EPS) and the Global Ensemble Forecasting System (GEFS) from the National Centers for Environmental Prediction (NCEP), which provide the IC and LBC perturbations. The investigation is carried out for a 51-day period during summer 2010 over central Europe. The results indicate that forcing of the regional ensemble with GEFS performs better for surface parameters, whereas at upper levels forcing with ECMWF-EPS is superior. Using perturbations from GEFS lead to a considerably higher spread in ALADIN-LAEF, which is beneficial near the surface where regional EPSs are usually underdispersive. At upper levels, forcing with GEFS leads to an overdispersion of ALADIN-LAEF as a result of the large spread of some parameters, where forcing ALADIN-LAEF with ECMWF-EPS provides statistically more reliable forecasts. The results indicate that the best global EPS might not always provide the best ICs and LBCs for a regional ensemble.

scholarly journals Effects of Aqua-Dispersing Nano-Binder on Clay Conductivity at Different Temperatures

2019 ◽  
Vol 11 (18) ◽  
pp. 4859
Author(s):  
Cuiying Zhou ◽  
Xingxing Ge ◽  
Wei Huang ◽  
Dexian Li ◽  
Zhen Liu
Keyword(s):  
Ecological Restoration ◽  
Soil Amendment ◽  
Large Scale ◽  
Soil Amendments ◽  
Quantitative Relationship ◽  
Silty Clay ◽  
Research Subjects ◽  
Nutrient Storage ◽  
Starting Point ◽  
The Impact

Soil nutrients are the basis of ecological remediation. Soil amendments can form a reticular membrane structure on the soil surface to increase nutrient storage and alleviate nutrient imbalances, and are affected by the environmental temperature. At present, the qualitative evaluation of the effect of soil amendment is mainly based on vegetative growth. However, with the increasing use of soil amendments, how to conveniently and quantitatively evaluate the impact of soil amendments on ecological restoration under different temperature conditions from the perspective of soil urgently needs to be solved. Therefore, a new soil amendment named aqua-dispersing nano-binder (ADNB) and silty clay that is commonly used for ecological restoration in South China were used as research subjects, and the important soil nutrient storage capacity—soil conductivity index—was used as the starting point to find solutions to the above problems. We independently developed a multifunctional instrument to measure the soil amendment concentration. Clay conductivity measurements were used by adding different concentrations of ADNB within the range of 0 to 50 °C, and the mechanism by which temperature and ADNB affect the conductivity of clay was revealed. In addition, the quantitative relationship between the clay conductivity, ambient temperature and concentration of ADNB was elucidated. According to the growth conditions of melinis minutiflora and pigeon pea under different concentrations of ADNB, the optimal ADNB concentration needed to improve ecological restoration was obtained, which provided a new way to evaluate the effects of the large-scale use of soil modifiers on ecological restoration.

The Next ‘Spring’ is Certain to Come – and Certain to be Missed

2014 ◽  
Vol 6 (4) ◽  
pp. 382-406 ◽  
Author(s):  
Witold Mucha
Keyword(s):  
Large Scale ◽  
Task Force ◽  
Authoritarian Regimes ◽  
The Political ◽  
International Crisis ◽  
Starting Point ◽  
To Come ◽  
International Crisis Group ◽  
The Arab Spring ◽  
The Impact

The Arab Spring took policymakers and academics by surprise. The starting point, the scope, nor the impact had been seen coming. This was primarily because of academics’ irrevocable belief in the stabilising power of authoritarian regimes. In light of this failing, the article will critically discuss the production of crisis knowledge on the basis of four major early warning tools. These are World Bank’s greed/grievance model, the predictive model by the Political Instability Task Force, the risk and capacity approach applied by the Failed States Index, and the International Crisis Group. The article will add to the debate in two ways. First, the analysis will show that prevention research can be biased in ways that crucially influence policymakers’ assessment of states at risk. Second, the article will argue in favour of a complementary perspective that includes the analysis of conflicts that do not erupt into large-scale violence against all odds (so-called ‘negative cases’).

scholarly journals Congruent evolutionary responses of European steppe biota to late Quaternary climate change: insights from convolutional neural network based demographic modeling

2021 ◽  
Author(s):  
Philipp Kirschner ◽  
Manolo Perez ◽  
Eliška Záveská ◽  
Isabel Sanmartin ◽  
Laurent Marquer ◽  
...  
Keyword(s):  
Large Scale ◽  
Late Quaternary ◽  
Demographic History ◽  
Climatic Oscillations ◽  
Vegetation Shifts ◽  
Demographic Modeling ◽  
Quaternary Climate ◽  
Eurasian Steppe ◽  
Novel Approach ◽  
The Impact

Abstract Quaternary climatic oscillations had a large impact on European biogeography. Alternation of cold and warm stages caused recurrent glaciations, massive vegetation shifts and large-scale range alterations in many species. The Eurasian steppe biome and its grasslands are a noteworthy example; they underwent climate-driven, large-scale contractions during warm stages and expansions during cold stages. Here, we evaluate the impact of these range alterations on the late Quaternary demography of phylogenetically unrelated plant and insect species, typical of the Eurasian steppes. We contrast three explicit demographic hypotheses by applying a novel approach combining Convolutional Neural Networks with Approximate Bayesian Computation. We identified congruent demographic responses of cold stage expansions and warm stage contractions across all species, but also species-specific effects. The demographic history of Eurasian steppe biota reflects major paleoecological turning points of the late Quaternary, and emphasizes the role of the climate as a driving force behind patterns of genetic variance.

Sign in / Sign up

Export Citation Format

Share Document